Analytical approach:
This analysis was based on a trial that investigated the efficacy of the CATCH programme on the prevalence of adult obesity. A model was constructed to extrapolate these results up to the ages of 40 to 64 years. The authors stated that the analysis was carried out from the perspective of society.
Effectiveness data:
The proportions of overweight and at-risk of overweight children at the age of 11 were derived from the CATCH trial (Coleman, et al. 2005, see 'Other Publications of Related Interest' below for bibliographic details). This trial followed a cohort of children from third grade (age eight) to fifth grade (age 11). They were from four randomly selected intervention schools (199 girls and 224 boys) and four matched control ones (224 girls and 249 boys) and 93% of them were Hispanic. The number of obese cases averted at ages 40 to 64 years, due to the CATCH programme, was predicted using a lifetime obesity progression model and data from the National Health and Nutrition Examination Study (NHANES I), the NHANES I Epidemiologic Followup Study (NHEFS), and a study, which predicted obesity in young adulthood from childhood and parental obesity (Whitaker, et al. 1997, see 'Other Publications of Related Interest' below for bibliographic details). The key clinical endpoint was the number of overweight cases averted.
Monetary benefit and utility valuations:
The impact of a reduction in BMI on the health-related quality of life was based on activity scores derived from the National Health Interview Survey (NHIS). In this survey, health state values were assigned ranging from 0.1 (limited with poor health) up to 1.0 (no limitation with excellent health). These estimates were then combined with the life expectancy estimates from a published study (Peeters, et al. 2003, see 'Other Publications of Related Interest' below for bibliographic details).
Measure of benefit:
: The measures of benefit were quality-adjusted life-years (QALYs) gained and a monetary valuation of health benefit. The utility estimates were combined with life expectancy estimates from a published study (Peeters, et al. 2003) to derive the QALYs for each health state. Future QALYs were discounted at 3%.
Cost data:
The economic analysis included the costs of the intervention, medical costs, and productivity costs. The intervention costs included CATCH staff wages and teacher training costs. A published study (Oster, et al. 1999, see 'Other Publications of Related Interest' below for bibliographic details) was used to derive the medical costs of being overweight that were averted due to the intervention. This included the costs associated with hypertension, hypercholesterolaemia, type 2 diabetes, cardiovascular disease, and stroke. The productivity costs averted were estimated using the number of sick days per year for obese adults compared with non-obese adults. The NHIS data was used to project the lost work days due to obesity. The median wage was derived from the US Department of Labor, Bureau of Labor Statistics Current Population Survey. All costs were in US dollars ($) and the price year was 2004. Future costs were discounted at an annual rate of 3%.
Analysis of uncertainty:
A probabilistic sensitivity analysis was carried out, based on 1,000 independent simulations. The results of the sensitivity analysis were reported as means and 95% confidence intervals.
